Various forms of lightening arresters and power surge protective devices are known in the prior art. Such devices may for example protect a given circuit in a home or other building against surges caused by lightening or the like. However, these devices offer no protection whatsoever to electrical appliances which may be plugged in to the protective circuit, where the amperage on which the appliance operates is far below the amperage in the protected circuit to which the circuit protecting device responds.
U.S. Pat. No. 3,539,961 Worthington discloses an isolator for protecting an appliance from the destructive effect of excessive power. The Worthington device employs a fusible wire which disintegrates at a preselected amperage such as 10 amps. As a consequence, this device is only effective when used with one particular appliance which happens to operate on the same amperage with which the device is matched. An appliance operating on a significantly lower current value would not be protected by the device and could be damaged or destroyed before the fusible wire disintegrated. An appliance requiring a greater amperage than that which will cause the fusible wire to fail would not run at all because the fusible wire will consume itself at a preselected lower amperage.
Accordingly, the objective of this invention is to provide a greatly improved protective device or isolator for appliances of all types requiring differing ranges of amperages to operate. The device embodied in the invention is provided with readily replaceable fuses directly in the power line leading to the appliance, and these fuses match up with the amperage required to operate a particular appliance with safety at full protection against abnormal power surges. The fuses of the device are chosen to enable the appliance to receive the required current, and not too much or too little. By merely properly selecting the fuses to match up with the current drawing requirements of various appliances, any and all appliances can be protected. The device also possesses a necessary and critical escape route for excessive power surges due to lightening, etc. This escape route prevents the current surges from arcing or jumping the gap between the end terminals of blown fuses and thereby reaching the appliance. A grounding power stop element is clipped onto the glass bodies of the fuses relatively near corresponding terminals thereof so that any abnormal surge of power is routed directly to the grounding power stop and safely grounded and prevented from jumping the gap to the terminals at the remote ends of the fuses connected with the appliance.
While the prior art does contain teachings of fused protective devices as in U.S. Pat. No. 1,892,567 Craddock, there is no provision in any known prior art device to prevent current surges from jumping the gap between terminals of blown fuses and thereby reaching an appliance.
Therefore, in essence, the present invention possesses two main advantages and capabilities not possessed by any prior art device. First, the device is completely effective to protect any and all appliances from damage caused by power surges through the use of readily interchangeable fuses chosen to meet the requirements of any appliance by delivering to that appliance only the amperage which it requires, and not too much or too little amperage. Second, by providing the unique grounding power stop which prevents excessive current surges from jumping the gap of blown fuses in the device, it become virtually impossible for an appliance to be damaged by lightening or the like.